Ink-based digital printing systems include an imaging member having an imaging surface such as a plate or blanket. The imaging surface must meet a range of requirements to enable high speed variable data ink-based digital printing. In related art systems, for example, the imaging surface must be configured for wetting the surface with dampening fluid, and pinning the dampening fluid thereon. The imaging surface must be configured for absorbing optical radiation from a laser imaging system, wetting and pinning of ink subsequently applied to the imaging member surface, and release of the ink from the surface.
The dampening fluid prevents ink from transferring to the plate at non-printing areas, or background or non-image areas. The printing areas are areas on the imaging member surface on which dampening fluid is volatilized after exposing the applied dampening fluid layer to radiation. The non-printing areas are areas on the imaging member surface on which dampening fluid remains, being outside the zones of exposure to radiation. Exemplary imaging member surface materials that have been found to be useful for ink-based digital printing include hydrophobic polymers such as silicones, partially or fully fluorinated fluorosilicones and FKM fluoroelastomers. Exemplary dampening fluids that have been found to be compatible for wetting the above-mentioned imaging member surface materials and suitable for ink-based digital printing include hydrophobic fluids such as hydrocarbons, fluorocarbons, fluoroethers, organosiloxanes, fluoro-organosiloxanes. Concerns about using these hydrophobic fluids relate to the containment and capture of volatilized fluids that may not be vented into the environment, or precluded from remaining in significant amounts on the printed matter. Water is a desirable dampening fluid for offset printing because it is inexpensive, and environmentally friendly, and therefore does not require volatilized fluid recapture or monitoring of hydrophobic fluids on the prints.